Alva Noë, Out of our heads. Why you are not your brain, and other lessons from the biology of consciousness, Hill and Wang 2009
Matters are made worse by the fact that the eyes move almost continuously. Several times a second they jitter and bounce; they also make saccades and micro-saccades-that is, sharp, ballistic movements. As a result, the projection of an object you perceive to be still in facts jumps around on your eyeball, and when you track a moving object, its image stays still on your retina while that of the stationary background races across your eyes. Again, in order to explain how we manage to experience a stable visual world, we need to suppose, it seems, that the ability is achieved at some later stage in the processing of the original retinal information.
The world is not a construction of the brain, nor is it a product of our own conscious efforts. It is there for us; we are here in it. The conscious mind is not inside us; it is, it would be better to say, a kind of active attunement to the world, an achieved integration. It is the world itself, all around, that fixes the nature of conscious experience.
The retinal image is an image in a mathematical sense; it is a projection or a mapping. The retinal image is not an image in the sense of a picture – or, if it is, this is entirely accidental. How it looks, or how it reads, plays no role in its performance of its neurophysiological job description. Once we appreciate that the retinal image isn’t something that we see, we lose a grip even on what it means to say that it is upside-down. Upside-down, one must ask relative to what? Who’s to say what counts as upside-down in the head relative to the tasks faced by the nervous system?
Again, we don’t experience the retinal image; we don’t experience any image , in that sense. We experience the world.